A conventional gas sensor includes a sensing element fastened sealedly in a housing. The sensing element is typically configured as a planar sensing element that has a first electrode exposed to a measured gas and a second electrode exposed to a reference gas. In order to deliver a reference gas onto the reference gas electrode, there is provided inside the sensing element a reference gas conduit, running in its longitudinal extension, which can be connected, at an end of the sensing element remote from the measured gas, to a reference gas source, for example the atmosphere. The reference gas conduit terminates at one end surface of the sensing element, and is connected to the reference gas source via a retaining and sealing element of the sensing element that is fastened in a housing of the gas sensor.
For example, German Patent No. 41 26 378 describes a conventional gas sensor. It is disadvantageous in this context that the reference gas conduit terminating at the end face cannot be adequately sealed against possible contaminants. In order to prevent undesired signal falsification, however, the reference gas conduit must be securely sealed against the penetration of substances, for example outside gases, which might falsify the reference gas.